Chronic infections caused by hepatitis B virus affect hundreds of millions of people worldwide and may lead to life-threatening conditions like cirrhosis and cancer. New safer and more effective therapies are needed to prevent the end stage liver diseases that cause one million hepatitis-related deaths a year. This contract utilizes the HBV transgenic mouse model to screen for and evaluate new antivirals. This model is smaller (less drug needed), cheaper and more readily available than other models, and it actively produces the human hepatitis B virus. Many classes of antivirals and immunomodulators are tested.